Kurds say they have taken Mosul Dam

(CNN) -- Kurdish forces have control of Mosul Dam, said Hemin Hawrami, the foreign relations head for the Kurdistan Democratic Party. Kurdish forces had been battling to retake the dam, which ISIS militants had seized.

The dam has been the center of an intense battle in northern Iraq between the Islamic extremists and Kurdish forces that were trying to retake it with the help of U.S. airstrikes.

The stakes are huge for the millions of Iraqis who live downstream from the dam, the largest in the country.

"If you control the Mosul dam, you can threaten just about everybody -- a very substantial part of Iraq -- with flooding, with lack of electricity, with lack of water," Daniel Pipes, president of the Middle East Forum, told CNN. "It's a horrendous prospect."

Built in the early 1980s under former Iraqi dictator Saddam Hussein, the dam sits on the Tigris River about 50 kilometers (30 miles) north of the city of Mosul. It serves as a key source of electricity, irrigation and flood protection.

When ISIS militants seized the dam this month, many feared it could be used as a weapon.

Water in war

ISIS has a track record of attacking its enemies with water.

This year, its fighters opened the gates on the Falluja Dam in central Iraq after seizing it in an effort to stop an Iraqi military advance. The water from the dam flooded a number of villages.

"ISIS has already used other smaller dams to gain control of territory, to pressure Sunnis to support them and to punish the Shiites," Pipes said this month.

The 3.2-kilometer-long Mosul Dam holds back as much as 12.5 million cubic meters of water, according to Engineering News-Record, a construction industry website.

If the structure were to give way, it would unleash a wall of water tens of feet tall that would race down the Tigris toward Mosul and its 1.7 million inhabitants. It would also bring flooding to major cities farther downstream, including Baghdad.

"The failure of the Mosul Dam could threaten the lives of large numbers of civilians, endanger U.S. personnel and facilities, including the U.S. Embassy in Baghdad, and prevent the Iraqi government from providing critical services to the Iraqi populace," U.S. President Barack Obama said in a letter to Congress on Sunday, explaining the airstrikes near the dam.

'A source of influence'

Pipes compared the scenario of the dam being destroyed to the Chinese Nationalist government's decision to destroy a crucial dike on the Yellow River in 1938 to try to halt the advance of Japanese troops. The move caused a flood that is estimated to have killed hundreds of thousands of Chinese people.

Some analysts, however, say they think it's unlikely ISIS would go as far as breaching the dam, putting in danger Mosul, a city the militants control.

"You don't want to have the cataclysmic event where, if this dam were to break, you would run the risk of flooding downstream along the Tigris," said retired Maj. Gen. James "Spider" Marks, a CNN military analyst.

"I would think that ISIS wants to retain control of that dam and would want to maintain its integrity, because it generates this electric power and they want to be able to use that as a weapon system to those who are under their control," he said.

Water is in increasingly short supply across the Middle East and has been linked to a large number of conflicts worldwide.

"They can use this as a source of influence," Pipes said.

'Very poor foundation'

But even if the militant group doesn't try to destroy the dam, concerns remain about its sturdiness.

A U.S. Army Corps of Engineers report in 2006 said that what made the dam especially dangerous was the risk of internal erosion of its foundations.

The structure is built on layers of soil that dissolve or erode in water.

The Army Corps said the dam was "constructed on a very poor foundation" that wasn't designed for the conditions.

Seepage has plagued the structure since the reservoir behind it was filled, according to a U.S. government report in 2007, and sinkholes have appeared near the structure, suggesting problems beneath the surface.

During the American military occupation of Iraq, U.S. authorities spent tens of millions of dollars on short-term repairs on the dam.

But with the immense structure now in the midst of a conflict zone, it remains unclear if it will get the maintenance it needs anytime soon.